Remove linq from BaseConfigurationComparer

Fixes #2464

src/Microsoft.IdentityModel.Tokens/BaseConfigurationComparer.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT License.
 
 using System.Collections.Generic;
-using System.Linq;
 
 namespace Microsoft.IdentityModel.Tokens
 {
@@ -17,22 +16,41 @@ public bool Equals(BaseConfiguration config1, BaseConfiguration config2)
                 return true;
             else if (config1 == null || config2 == null)
                 return false;
-            else if (config1.Issuer == config2.Issuer && config1.SigningKeys.Count == config2.SigningKeys.Count
-                     && !config1.SigningKeys.Select(x => x.InternalId).Except(config2.SigningKeys.Select(x => x.InternalId)).Any())
-                return true;
             else
-                return false;
+            {
+                if (config1.Issuer != config2.Issuer)
+                    return false;
+
+                if (config1.SigningKeys.Count != config2.SigningKeys.Count)
+                    return false;
+
+                foreach (var key in config1.SigningKeys)
+                {
+                    if (!ContainsKeyWithInternalId(config2, key.InternalId))
+                        return false;
+                }
+            }
+
+            return true;
+        }
+
+        private static bool ContainsKeyWithInternalId(BaseConfiguration config, string internalId)
+        {
+            foreach(var key in config.SigningKeys)
+                if (key.InternalId == internalId)
+                    return true;
+
+            return false;
         }
 
         public int GetHashCode(BaseConfiguration config)
         {
             int defaultHash = string.Empty.GetHashCode();
             int hashCode = defaultHash;
             hashCode ^= string.IsNullOrEmpty(config.Issuer) ? defaultHash : config.Issuer.GetHashCode();
-            foreach(string internalId in config.SigningKeys.Select(x => x.InternalId))
-            {
-                hashCode ^= internalId.GetHashCode();
-            }
+
+            foreach (var key in config.SigningKeys)
+                hashCode ^= key.InternalId.GetHashCode();
 
             return hashCode;
         }

test/Microsoft.IdentityModel.Tokens.Tests/BaseConfigurationComparerTests.cs

@@ -0,0 +1,130 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Microsoft.IdentityModel.TestUtils;
+using Xunit;
+
+namespace Microsoft.IdentityModel.Tokens.Tests
+{
+    public class BaseConfigurationComparerTests
+    {
+        [Theory, MemberData(nameof(ComparerTheoryData))]
+        public void Compare(BaseConfigurationComparerTheoryData theoryData)
+        {
+            var context = TestUtilities.WriteHeader($"{this}.Compare", theoryData);
+            var comparer = new BaseConfigurationComparer();
+            var result = comparer.Equals(theoryData.ConfigurationA, theoryData.ConfigurationB);
+            Assert.Equal(theoryData.ShouldBeEqual, result);
+        }
+
+        public static TheoryData<BaseConfigurationComparerTheoryData> ComparerTheoryData()
+        {
+            var jsonWebKey1 = new TestConfiguration
+            {
+                Issuer = "http://example.com/issuer/1",
+            };
+
+            jsonWebKey1.SigningKeys.Add(DataSets.JsonWebKey1);
+
+            var jsonWebKey2 = new TestConfiguration
+            {
+                Issuer = "http://example.com/issuer/1",
+            };
+
+            jsonWebKey2.SigningKeys.Add(DataSets.JsonWebKey2);
+
+            var bothJsonWebKeys = new TestConfiguration
+            {
+                Issuer = "http://example.com/issuer/1",
+            };
+
+            bothJsonWebKeys.SigningKeys.Add(DataSets.JsonWebKey1);
+            bothJsonWebKeys.SigningKeys.Add(DataSets.JsonWebKey2);
+
+            return new TheoryData<BaseConfigurationComparerTheoryData>()
+            {
+                new()
+                {
+                    TestId = "Both null",
+                    ConfigurationA = null,
+                    ConfigurationB = null,
+                    ShouldBeEqual = true,
+                },
+                new()
+                {
+                    TestId = "B null",
+                    ConfigurationA = new TestConfiguration(),
+                    ConfigurationB = null,
+                    ShouldBeEqual = false,
+                },
+                new()
+                {
+                    TestId = "A null",
+                    ConfigurationA = null,
+                    ConfigurationB = new TestConfiguration(),
+                    ShouldBeEqual = false,
+                },
+                new()
+                {
+                    TestId = "Issuer mismatched",
+                    ConfigurationA = new TestConfiguration
+                    {
+                        Issuer = "http://example.com/issuer/1"
+                    },
+                    ConfigurationB = new TestConfiguration
+                    {
+                        Issuer = "http://example.com/issuer/2"
+                    },
+                    ShouldBeEqual = false,
+                },
+                new()
+                {
+                    TestId = "No Keys",
+                    ConfigurationA = new TestConfiguration
+                    {
+                        Issuer = "http://example.com/issuer/1",
+                    },
+                    ConfigurationB = new TestConfiguration
+                    {
+                        Issuer = "http://example.com/issuer/1"
+                    },
+                    ShouldBeEqual = true,
+                },
+                new()
+                {
+                    TestId = "different keys",
+                    ConfigurationA = jsonWebKey1,
+                    ConfigurationB = jsonWebKey2,
+                    ShouldBeEqual = false,
+                },
+                new()
+                {
+                    TestId = "same keys",
+                    ConfigurationA = jsonWebKey1,
+                    ConfigurationB = jsonWebKey1,
+                    ShouldBeEqual = true,
+                },
+                new ()
+                {
+                    TestId = "different number of keys",
+                    ConfigurationA = jsonWebKey1,
+                    ConfigurationB = bothJsonWebKeys,
+                    ShouldBeEqual = false,
+                },
+            };
+        }
+    }
+
+    public class BaseConfigurationComparerTheoryData : TheoryDataBase
+    {
+        public BaseConfiguration ConfigurationA { get; set; }
+
+        public BaseConfiguration ConfigurationB { get; set; }
+
+        public bool ShouldBeEqual { get; set; }
+    }
+
+    public class TestConfiguration : BaseConfiguration
+    {
+    }
+}